Mizrahi does not refer to 2nd generation immigrants [1]; it refers to descendants of local Jewish populations in the Middle East. While the Wikipedia demographics link you posted is technically accurate (the best kind of accurate), it doesn't correctly capture Mizrahi Jews, because Mizrahi means native to the Middle East, not specifically to the region called "Palestine," the modern borders of which were defined by the British after WWI. Those borders also include much, much more than just the "Palestine" you're referring to — it includes all of Jordan and part of Syria.
Prior to the British occupation, the entire region was part of the Ottoman Empire and had been for hundreds of years; the modern borders and boundaries of various countries were largely invented during the 20th century after the fall of the Ottoman Empire to the Allied Powers. When Israel was founded, most Mizrahi Jews moved to Israel due to extreme persecution in the Muslim-majority countries, which were mostly also all new countries carved up from the remains of the Ottoman Empire. Prior to the borders of the 20th century, these Jews were citizens of the Ottoman Empire just like everyone else in the region, and were native to the Middle East. (The Ottoman empire did have provinces, but they don't match the British borders or the post-British borders.)
Mizrahi Jews make up 3.2 million of Israel's Jewish inhabitants [1]. Israel's total Jewish population is 6.7 million [2], so they're about half.
Edit: Since this is frequently a contentious topic, I want to reiterate that I do not support the Israeli government's treatment of Palestinians. Israel's treatment of Palestinians is terrible. This post is meant to counter anti-Semitism, not criticism of Israel. In most of my posts in this thread I have also criticized Israel for its treatment of Palestinians. The fact that many Jews are native to the Middle East does not justify depriving Palestinians of land or self-determination. However, I think it's useful in these discussions to not rely on anti-Semitic tropes e.g. the idea that Jews are non-natives and of Jewish replacement. Jews are in fact natives of the Middle East and have been so longer than anyone else (well, ethnic Lebanese people actually give Jews a run for their money, but those are the two longest-dwelling ethnic groups in the region).
Edit 2: Since it looks like you're getting downvoted — FYI I didn't downvote you and I think your question was legitimate and wasn't ill-intentioned.
To quote the first Wikipedia link I posted in the comment that you're replying to, yes. "From 1948 to 1980, over 850,000 Mizrahi and Sephardi Jews were expelled, fled or evacuated from Arab and Muslim countries."
Hajj Amin al Huseini supposedly influenced the persecution of Mizrahi Jews all around the Middle East? That doesn’t seem very plausible, what real power and authority did this guy have over peoples outside of Palestine?
He was funded and supported by the Nazis to build up pan-Arab support for Jewish genocide, and lived in a variety of places both inside and outside of Palestine, including Germany and Egypt. He met with Adolf Hitler himself. In the late 1930s while living in Beirut he put a bounty on the head of any Jew, paying 10 pounds per murdered Jew. Here is the Wikipedia link: https://en.wikipedia.org/wiki/Amin_al-Husseini
A choice quote, of which there are many: "On 1 March 1944, while speaking on Radio Berlin, al-Husseini said: 'Arabs, rise as one man and fight for your sacred rights. Kill the Jews wherever you find them. This pleases God, history, and religion. This saves your honor. God is with you.'"
Note that the calls for genocide started well before 1948. He was fomenting genocide the entire time. His messages during WWII were extremely popular in the Arab world and upon his return to Palestine after the war "Arab leaders rushed to greet him ... and the masses accorded him an enthusiastic reception."
Prior to the British occupation, the entire region was part of the Ottoman Empire and had been for hundreds of years; the modern borders and boundaries of various countries were largely invented during the 20th century after the fall of the Ottoman Empire to the Allied Powers. When Israel was founded, most Mizrahi Jews moved to Israel due to extreme persecution in the Muslim-majority countries, which were mostly also all new countries carved up from the remains of the Ottoman Empire. Prior to the borders of the 20th century, these Jews were citizens of the Ottoman Empire just like everyone else in the region, and were native to the Middle East. (The Ottoman empire did have provinces, but they don't match the British borders or the post-British borders.)
Mizrahi Jews make up 3.2 million of Israel's Jewish inhabitants [1]. Israel's total Jewish population is 6.7 million [2], so they're about half.
Edit: Since this is frequently a contentious topic, I want to reiterate that I do not support the Israeli government's treatment of Palestinians. Israel's treatment of Palestinians is terrible. This post is meant to counter anti-Semitism, not criticism of Israel. In most of my posts in this thread I have also criticized Israel for its treatment of Palestinians. The fact that many Jews are native to the Middle East does not justify depriving Palestinians of land or self-determination. However, I think it's useful in these discussions to not rely on anti-Semitic tropes e.g. the idea that Jews are non-natives and of Jewish replacement. Jews are in fact natives of the Middle East and have been so longer than anyone else (well, ethnic Lebanese people actually give Jews a run for their money, but those are the two longest-dwelling ethnic groups in the region).
Edit 2: Since it looks like you're getting downvoted — FYI I didn't downvote you and I think your question was legitimate and wasn't ill-intentioned.
1: https://en.m.wikipedia.org/wiki/Mizrahi_Jews
2: https://en.m.wikipedia.org/wiki/Israeli_Jews